Plasma is used in various production sites. For example, in the field of manufacturing of semiconductor circuits, a surface of a semiconductor circuit to be bonded is cleaned using plasma.
As one example of plasma generating apparatuses, Japanese Unexamined Patent Application Publication No. 2002-343599 discloses an apparatus configured such that a wire is disposed at an axial core of a glass tube in which an argon gas is introduced, and that a high frequency coil and an ignition coil are wound at a tip portion of the glass tube (Patent Document 1). According to this apparatus, after an argon gas is introduced into the glass tube and a flow of a plasma gas is stabilized, a high frequency power is supplied to the high frequency coil from a high frequency power source, and then a high voltage is applied to the ignition coil, and whereby a discharge is generated and plasma is generated.
Further, Japanese Unexamined Patent Application Publication No. 2003-328138 discloses a plasma ignition mechanism of igniting plasma by applying a high voltage to a plasma ignition coil including a wire from an igniter, and by inducing a discharge between the plasma ignition coil and the wire (FIG. 3, Patent Document 2).
Moreover, Japanese Unexamined Patent Application Publication No. 2006-104545 discloses a micro plasma reactor configured such that around an inner tube of a plasma flame off through which a high-melting conducting wire is inserted is enclosed by an outer tube of a plasma flame off in which a mixed gas circulates, and a discharge is started by an externally provided igniter (FIGS. 1-6, Patent Document 3).
Furthermore, Japanese Unexamined Patent Application Publication No. H06-215894 discloses a radio-frequency plasma power supply device that supplies high frequency power between electrodes in a plasma chamber via an impedance matching circuit (Patent Document 4). According to this device, a voltage value supplied to an FET of a power amplifier is set to be low during a time period until power output impedance and impedance in the plasma chamber match, thereby preventing an FET from being damaged due to a reflected wave.